haraldwolff/qemu-patch-raspberry4
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libvhost-user: Send messages with no data

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The response to a VHOST_USER_POSTCOPY_ADVISE contains a fd but doesn't
actually contain any data.   FIx vu_message_write so that it doesn't
do a 0-byte write() call, since this was ending up with rc=0
that was confusing the error handling code.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Dr. David Alan Gilbert 2018-05-04 10:53:46 +01:00 committed by Michael S. Tsirkin
parent 9952e807fd
commit e3638151da
1 changed files with 9 additions and 7 deletions
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16
contrib/libvhost-user/libvhost-user.c
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@ -323,13 +323,15 @@ vu_message_write(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
rc = sendmsg(conn_fd, &msg, 0);
} while (rc < 0 && (errno == EINTR || errno == EAGAIN));
do {
if (vmsg->data) {
rc = write(conn_fd, vmsg->data, vmsg->size);
} else {
rc = write(conn_fd, p + VHOST_USER_HDR_SIZE, vmsg->size);
}
} while (rc < 0 && (errno == EINTR || errno == EAGAIN));
if (vmsg->size) {
do {
if (vmsg->data) {
rc = write(conn_fd, vmsg->data, vmsg->size);
} else {
rc = write(conn_fd, p + VHOST_USER_HDR_SIZE, vmsg->size);
}
} while (rc < 0 && (errno == EINTR || errno == EAGAIN));
}
if (rc <= 0) {
vu_panic(dev, "Error while writing: %s", strerror(errno));